Embodiments of this invention relate to geography, geographic information systems and digital cartography. More particularly embodiments of this invention relate to a system and method for establishing a map page layout over an area together with a local/universal page and grid numbering system in a geographic referencing system and linking global positioning system (GPS)—defined locations directly to the page and grid of a map atlas or other publication.
Every location in the U.S. is served by public and private map publications that have no relationship to locational coordinates provided by GPS units. Some publications include tick marks for lat/long, Universal Transverse Mercator (UTM), state plane, Township-and-Range (TSR), and other geographic reference systems at the edge of or within their maps, but there is no logical connection to the page number in the map publication. The source of this problem is that there is no algorithmic method of generating, from a projection's coordinates, a local page and grid numbering system to be used in local street atlases, parcel maps and other mapping products.
The geographic referencing systems in digital maps and GPS units are almost always completely different from the geographic referencing systems in those map publications that are in book form. There is no easy or standard way to translate the computerized map coordinates to the pages of the map publications.
By way of illustration, the U.S. Geological Survey (USGS) publishes large-scale (1:24000) maps of the U.S. (referred to as “QuadSheets”) for using geographic coordinates (“latitude/longitude”) as the basis for mapsheet tiling. Commercial atlas publishers such as DeLorme have published QuadSheets as map pages. However, the USGS product has no associated page and grid system, and the commercial product page and grid arrangement is not algorithmically derived.
The UTM projection is an excellent referencing system that is useful as a grid reference and is featured in many commonly available GPS units. In the UTM grid, the world is divided into 60 north-south zones, each covering a strip 6° wide in longitude. These zones are numbered consecutively beginning with Zone 1, between 180° and 174° west longitude, and progressing eastward to Zone 60, between 174° and 180° east longitude. Thus, the conterminous 48 States are covered by 10 zones, from Zone 10 on the west coast through Zone 19 in New England. In each zone, coordinates are measured north and east in meters. The northing values are measured continuously from zero at the Equator, in a northerly direction. To avoid negative numbers for locations south of the Equator, NIMA's cartographers assigned the Equator an arbitrary false northing value of 10,000,000 meters. A central meridian through the middle of each 6° zone is assigned an easting value of 500,000 meters. Grid values to the west of this central meridian are less than 500,000; to the east, more than 500,000.
The United States National Grid (USNG) is an alphanumeric point reference system that overlays the UTM numerical coordinate system. The USNG provides a system for identifying locations and for specifying one-kilometer square grids. For example, the Washington Monument is located in the middle of column 23 and row 06 which is Grid 2306 of its local 100,000-square meter zone. Map publishers can publish wall maps and folding maps that use the USNG two-digit grid designations to indicate column and row and can create indexes of street names and points of interest that provide the four digit grid (two digits column and two digits row) as a reference. Map publishers can also use these grid designations on map pages in street atlases.
While useful, the UTM and USNG are not designed for the page and grid numbering of map publications. The United Kingdom and several other foreign countries have a referencing system similar to the U.S. National Grid, but they, too, are not designed for the page and grid numbering of map publications. Further, there is no standard method of relating USNG grids to the pages of the local street atlas, and there is no system that converts the USNG grids to the page number (or page and local grid) of the page that contains that grid.
As the U.S. National Grid comes into common usage as a geographic reference system, there will be a growing need for a geographical reference system that translates a USNG designation to a local page and grid designation in atlases that display the USNG. For example, assume the Washington Monument is on page 500 of an atlas. If a user of a street atlas wishes to find the location of Grid 2306 on a page of a mapbook, the user needs to consult a table of grid values that points the user to the page number of the page in the atlas. A lookup table which matches 2306 with 500 would be required. In fact, a page in an atlas will include many one-kilometer grids. A standard page will contain 24 grids, four grids wide by six grids tall. The lookup table would be required to point the user to the page and the (local) grid of the atlas. For example, if USNG grid 2306 were to equal Local Page 500 Grid A3, then the grid to the south, USNG Grid 2305 would equal Local Page 500 Grid A4, as shown in the following illustrative table:
USNG GridLPGNS PageLPGNS Grid2300540A32301540A22302540A12303500A62304500A52305500A42306500A32307500A22308500A12309460 A6,etc.. . . . . . 
Rand McNally uses a proprietary Lambert Conformal Conic projection and local page and grid referencing system that has a relationship to the map projection that allows it to be rendered in a GPS unit. However, the local system covers less than ten percent of the land area of the U.S. Further, the local grids were assigned in a non-algorithmic manner, so there is no algorithmic relationship to the local area covered.
U.S. Pat. No. 5,839,088, issued to Hancock and entitled, “Geographic Location Referencing System And Method,” describes a system and method for creating and using a location referencing address method associated with an established geographic information system. The location referencing address method has an arbitrary local referencing system that retains a known relationship with a global referencing system. While Hancock identifies locations in relationship to the position of local features, its utility is identification and transmission of locational coordinates, not map publishing. Further, Hancock does not provide a page and grid numbering system.
U.S. Pat. No. 5,848,373, issued to DeLorme et al. and entitled, “Computer Aided Map Location System,” describes a system for correlation and coordination of spatially related information between diverse media such as transitory digital electronic displays or other computer outputs and graphics, text, fixed media presentations such as printed sheet media including printed maps. However, DeLorme et al. does not address the issue of page and grid numbering.
What would be useful would be a system and method to convert the coordinates of a common projection (such as UTM) to a local page and grid numbering system. Such a system and method would employ an algorithm to create the page and grid layout of local map products.